This invention relates to audio signal control circuitry and more particularly to an audio signal amplitude detector for applying an audio signal above a predetermined amplitude to a speaker.
Motion picture theaters are often equipped with a stereo sound system having several pairs of speakers. At least one pair of speakers is located at the front of the theater on either side of the audience. A second pair of speakers is commonly located at the rear of the theater, again on either side of the audience. Under most circumstances, for example, when an actor or actress is talking, the audience is most comfortable when the sound comes only from the front pair of speakers so that the sound appears to come from the picture! It is dramatically effective to drive the rear pair of speakers for special effects such as explosions, loud noises and climaxes in the background music. One method for accomplishing this is to monitor the amplitude of the signal applied to the front pair of speakers and to close relays for connecting the rear pair of speakers to the sound system when the monitored amplitude exceeds a predetermined level. However, this arrangement produces an undesirably loud pop or click in the rear speakers when the relay is closed.